Preheat oven to 400°F, then butterfly chicken breast or cut a pocket. I personally cut a pocket over splitting the entire chicken in half
Prepare spinach by draining any excess water from it. If using fresh, wither the spinach and drain. If using frozen, melt the ice from spinach and drain well. Amount will be the same with both.
In a mixing bowl combine cream cheese, mozzarella cheese, drained spinach, garlic powder and onion powder.
Spoon spinach inside of chicken the secure chicken closed with toothpick or butchers twine. Salt and pepper chicken to taste.
In a pan on medium/high heat add chicken and sear both sides. Sear both sides well then place in oven for 15-20 until the chicken reaches proper done temperture.
Serve and becareful insides will be hot